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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: (10x+9) . x – (5x-1) . (2x+3) = 8

Toán Lớp 8: (10x+9) . x – (5x-1) . (2x+3) = 8

Comments ( 2 )

  1. (10x+9).x-(5x-1).(2x+3)=8
    =10x.x+9.x-(5x.2x+5x.3x-1.2x-1.3)=8
    ⇔10x^2+9x-(10x^2+15x-2x-3)=8
    ⇔10x^2+9x-(10x^2+13x-3)=8
    ⇔10x^2+9x-10x^2-13x+3=8
    ⇔10x^2-10x^2+9x-13x=8-3
    ⇔-4x=5
    ⇔x=-5/4
    Vậy x=-5/4.

  2. (10x+9) . x – (5x-1) . (2x+3) = 8
    10x^2+9x -5x+1 . (2x+3) = 8
    10x^2+9x -10x^2-15x+2x+3 = 8
    (10x^2-10x^2)+(9x+2x-15x)=8-3
    -4x=5
    x=-5/4
    Vậy x=-5/4
    Vote 5 sao bạn nhé
    CHÚC BẠN HỌC TỐT

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222-9+11+12:2*14+14 = ? ( )